JP7355688B2 - thickness measuring device - Google Patents

Description

The present invention relates to a thickness measuring device for measuring the thickness of a warped workpiece such as a semiconductor wafer.

When measuring the thickness of a workpiece such as a semiconductor wafer, the workpiece is held on a measurement table and the top surface of the workpiece is The thickness of the workpiece is measured by the height of the probe that is lowered and its tip touches.

Japanese Patent Application Publication No. 2002-039703

If the workpiece to be measured for thickness has a warp, for example, a concave shape, when the workpiece is held on the measurement table, there will be a gap between the top surface of the measurement table and the outer peripheral area of the bottom surface of the workpiece. A gap is created. If you measure the thickness of the workpiece with the gap created, the gauge head will measure the thickness of the workpiece as the thickness of the workpiece plus the size of the gap. There is a problem that the thickness of objects cannot be measured.
Therefore, in a thickness measuring device that measures the thickness of a workpiece by contacting the gauge head, there is a problem of being able to accurately measure the thickness of a warped workpiece.

In order to solve the above problems, the present invention is a thickness measuring device that measures the thickness of a warped workpiece by the height of a probe lowered onto the upper surface of the workpiece. A measurement table that holds the lower surface of the workpiece by suction, a center measurement stylus placed directly above the center of the measurement table, and a center measurement stylus spaced apart from the center measurement stylus in the radial direction of the measurement table; A plurality of radial measuring elements arranged at intervals in the radial direction, and a measuring element that lowers the central measuring element and then sequentially lowers the radial measuring elements in order from the center of the measuring table toward the outside. A thickness measuring device comprising a descent control means.

The measurement table has a center table that is placed directly below the center measuring element and holds the lower surface of the workpiece under suction, and a center opening that exposes the center table, and the workpiece that is suction-held by the center table. It is preferable to include a support table for supporting the lower surface of the workpiece, and rotation means for rotating the central table about the center of the central table.

Preferably, the measurement table includes a radial table disposed directly below each of the plurality of radial measuring elements, and the support table has a radial opening that exposes the radial table.

Preferably, the radial table is capable of suctioning and holding the workpiece, and when the radial measuring element descends, the radial table suction-holds the workpiece to measure the thickness of the workpiece.

The thickness measuring device according to the present invention, which measures the thickness of a workpiece by the height of a measuring stylus lowered onto the top surface of a warped workpiece, has a measuring table that suctions and holds the bottom surface of the workpiece with a holding surface. , a center measuring point placed directly above the center of the measuring table, a center measuring point spaced from the center measuring point in the radial direction of the measuring table, and a plurality of radial measuring points placed at intervals from each other in the radial direction of the measuring table. After lowering the center measuring element using the measuring element lowering control means, the radial measuring element is controlled to be lowered sequentially from the center of the measuring table outward. The workpiece is pushed from the center of the workpiece toward the outer circumference toward the holding surface located below to prevent the workpiece from becoming slack, and to gradually eliminate warpage and reduce the thickness while eliminating the gap between the workpiece and the holding surface. Since the measurement is performed, it is possible to accurately measure the thickness of a warped workpiece.

The measurement table has a center table that is placed directly below the center measuring tip and holds the bottom surface of the workpiece under suction, and a center opening that exposes the center table, and supports the bottom surface of the workpiece that is held under suction by the center table. and a support table for rotating the center table around the center of the center table, so that the workpiece can be held each time the thickness of the workpiece is measured using a plurality of radial measuring elements. By rotating the central table by a predetermined angle using the rotating means, it is possible to measure the thickness at a plurality of locations in the circumferential direction of the upper surface of the workpiece.

In the thickness measuring device according to the present invention, the measuring table includes a radial table disposed directly below each of the plurality of radial measuring elements, and the support table has a radial opening that exposes the radial table. , it becomes possible to measure the thickness of a workpiece using a plurality of radial measuring elements on a plurality of radial tables.

The radial table can hold the workpiece by suction, and when the radial measuring head descends, the radial table suctions and holds the workpiece, and by measuring the thickness of the workpiece, the holding surface and the workpiece are It is possible to more accurately measure the thickness of the workpiece without creating a gap between the workpiece and the workpiece.

It is a perspective view showing an example of a thickness measuring device. FIG. 2 is a cross-sectional view showing an example of a workpiece having a warped shape. FIG. 2 is a cross-sectional view illustrating a state in which the thickness of a warped workpiece is measured by a thickness measuring device. FIG. 3 is a plan view showing one center measurement point and 36 radial measurement points of the workpiece.

The thickness measuring device 1 shown in FIG. 1 is a device that measures the thickness of a workpiece 80 by measuring the height of a probe lowered onto the upper surface 802 of a workpiece 80 that has a warp (for example, a concave warp). There is a measuring table 3 that sucks and holds the lower surface 801 of the workpiece 80 with a holding surface, a center measuring stylus 42 disposed directly above the center of the measuring table 3, and a center measuring stylus 42 in the radial direction of the measuring table 3. A plurality (for example, three) of radial measuring elements are arranged at intervals and further spaced apart from each other in the radial direction of the measurement table 3, that is, a first radial measuring element 44, a second radial measuring element 45, After lowering the third radial measuring element 46 and the center measuring element 42, the first radial measuring element 44 to the third radial measuring element 46 are sequentially lowered from the center of the measuring table 3 toward the outside in the radial direction. The sensor head lowering control means 9 is provided.

The workpiece 80 shown in FIGS. 1 and 2 is, for example, a circular semiconductor wafer made of a silicon base material or the like, and a probe contacts the upper surface 802 facing upward. Note that the workpiece 80 may be made of gallium arsenide, sapphire, gallium nitride, resin, ceramics, silicon carbide, or the like other than silicon. The workpiece 80 may have a device such as an IC or an LSI formed thereon, or may not have a device formed thereon.

For example, in this embodiment, the workpiece 80 is entirely curved in a concave shape, that is, has a concave warp, as shown in FIG. Note that this concave warpage means that when the workpiece 80 is placed on the measurement table 3, the workpiece 80 is shaped like a bowl on the measurement table 3, that is, the upper surface 802 of the workpiece 80 is This is a warp that gradually becomes lower from the outer circumferential area to the central area. Note that the warp of the workpiece 80 is not limited to a concave warp, but a warp that is a midconvex shape in which the upper surface 802 of the workpiece 80 gradually becomes higher from the outer peripheral region to the central region. The upper surface 802 of the workpiece 80 may be warped in such a way that it randomly waves from the outer peripheral region to the central region.

In this embodiment, the measurement table 3 shown in FIGS. 1 and 3 includes a central table 30 that is placed directly below the center measuring element 42 and holds the lower surface 801 of the workpiece 80 by suction, and a plurality of first radial measuring elements. 44, a first radial table 321, a second radial table 322, a third radial table 323, and a central table 30 arranged directly below each of the second radial measuring element 45 and the third radial measuring element 46. and a radial opening 331, a radial opening 332, and a radial opening 333 that expose the first radial table 321, the second radial table 322, or the third radial table 323, respectively. A support table 33 that supports a lower surface 801 of a workpiece 80 that is suction-held by the central table 30 is provided.

The support table 33 has, for example, a circular plate shape in plan view, and has a larger diameter than the central table 30, the first radial table 321, the second radial table 322, and the third radial table 323. There is. The flat upper surface of the support table 33 serves as a support surface 335 that supports the lower surface 801 of the workpiece 80. For example, a circular central opening 330 is formed through the center of the support table 33 in the Z-axis direction (vertical direction). The central opening 330 is large enough to allow the central table 30 to rotate about the rotation axis in the Z-axis direction.

In this embodiment, three radial openings 331, 332, and 333 are formed through the support table 33 at predetermined intervals from the central opening 330 toward the outside in the radial direction. . For example, the interval between the radial opening 331 and the radial opening 332 and the interval between the radial opening 332 and the radial opening 333 are the same. For example, the support table 33 is supported by a support column 339 connected to its lower surface.

The central table 30, which is housed in the central opening 330 with the holding surface 300 exposed, has, for example, a circular external shape in a plan view, and the lower surface thereof has a mechanism for rotating the central table 30 around the center of the central table 30. A rotating means 36 is connected thereto. The rotating means 36 includes a spindle 362 that is connected to the central table 30 and whose axial direction is the Z-axis direction, and a motor 363 that is a rotational drive source that rotationally drives the spindle 362.

The flat upper surface of the central table 30 serves as a holding surface 300 that holds the workpiece 80 under suction, and for example, a suction hole 303 that transmits suction force to the holding surface 300 is opened in the center of the holding surface 300. . A central suction path 390 communicates with the suction hole 303, and the central suction path 390 is connected to an ejector mechanism, a vacuum generator, etc. through a spindle 362 and a rotary joint 398 (only shown in FIG. 3) or a joint (not shown). It communicates with a suction source 39. For example, a central opening/closing valve 391 such as a solenoid valve is disposed within the central suction path 390 to switch between a state in which the central suction path 390 communicates with the suction source 39 and a state in which it does not communicate with the suction source 39 .
The holding surface 300 may be made of a porous member, a plurality of suction holes 303 may be formed in the holding surface 300 at equal intervals in the circumferential direction and the radial direction, or suction grooves may be formed. You can leave it there.

A first radial table 321, a second radial table 322, and a third radial table 323 having the same structure are housed in the three radial openings 331, 332, and 333, respectively. There is. In this embodiment, the first radial table 321, the second radial table 322, and the third radial table 323 are capable of suctioning and holding the workpiece 80. That is, the flat upper surfaces of the first radial table 321 to the third radial table 323 serve as holding surfaces that suction and hold the workpiece 80, and the radial suction path 392, the radial suction path 393, or the radial suction path 394 Suction holes communicating with the suction source 39 via the suction holes are respectively open. A radial opening/closing valve 395, a radial opening/closing valve 396, and a radial opening/closing valve 397, such as solenoid valves, are provided in the radial suction passage 392, the radial suction passage 393, and the radial suction passage 394, respectively. .
Note that the holding surfaces of the first radial table 321, the second radial table 322, and the third radial table 323 may be made of a porous member or the like.
Further, one radial opening/closing valve is disposed in the suction passage where the radial suction passage 392, the radial suction passage 393, and the radial suction passage 394 merge to become one and communicate with the suction source 39. The communication between the suction source 39 and the radial suction path 392, the radial suction path 393, and the radial suction path 394 may be switched by opening and closing the one radial opening/closing valve.

For example, the first radial table 321 to the third radial table 323 are each supported by a fixing member 325 shown in FIG. The radial opening 331, the radial opening 332 , and the radial opening 333, respectively.
That is, the measurement table 3 includes a rotating central table 30, a fixed support table 33, and first to third radial tables 321 to 323.

In this embodiment, the support surface 335 of the support table 33, the suction holding surface 300 of the central table 30, and the suction holding surfaces of the first radial table 321, the second radial table 322, and the third radial table 323 are Although the heights are flush, for example, the support surface 335 of the support table 33 may be located at a slightly lower height position than the others.

The center measuring element 42, which is disposed directly above the center of the measuring table 3 shown in FIGS. 1 and 3, that is, directly above the center of the center table 30, is made of diamond or the like and has an R-shaped tip and a Z-axis A contact 420 extending in the direction contacts the top surface 802 of the workpiece 80 . The measuring head main body 421 that supports the contact 420 knows the height position of the holding surface 300 in advance, and the contact 420 is brought into contact with the upper surface 802 of the workpiece 80 held by the holding surface 300. The thickness of the workpiece 80 can be measured from the height position of the upper surface 802 of the workpiece 80, that is, the difference between the height position of the tip of the contact 420 and the height position of the holding surface 300.

The center sensor 42 can be moved up and down in the Z-axis direction (vertical direction) by a central cylinder mechanism 90 such as an electric cylinder or an air cylinder shown in FIG. It is controlled by control means 9.

As shown in FIG. 1, a first radial measuring element 44, a second radial measuring element 45, and a third radial measuring element 46 are arranged at intervals in the radial direction of the center measuring element 42 and the measuring table 3. are located directly above the centers of the first radial table 321, the second radial table 322, and the third radial table 323, respectively. The structures of the first radial measuring element 44, the second radial measuring element 45, and the third radial measuring element 46 are similar to the center measuring element 42 described above.

The first radial gauge head 44, the second radial gauge head 45, and the third radial gauge head 46 are connected to a first radial cylinder mechanism 91 and a second radial gauge head, respectively, which are controlled by the gauge head lowering control means 9. The directional cylinder mechanism 92 and the third radial cylinder mechanism 93 allow vertical movement in the Z-axis direction.

For example, the probe lowering control means 9, which is composed of a CPU that performs arithmetic processing according to a control program, a storage element such as a memory, etc., includes a central cylinder mechanism 90, a first radial cylinder mechanism 91, a second radial cylinder mechanism 91, and a second radial cylinder mechanism 90 as described above. It is electrically connected to the cylinder mechanism 92, the third radial cylinder mechanism 93, etc., and receives information about the rotation angle of the central table 30 by the rotation means 36 via a wireless or wired communication path. Furthermore, it is possible to supply power for opening and closing the central opening/closing valve 391 and the radial opening/closing valves 395 to 397.

The operation of the thickness measuring device 1 when measuring the thickness of a warped workpiece 80 using the thickness measuring device 1 shown in FIG. 1 will be described below.
First, the workpiece 80 is placed on the holding surface 300 with the upper surface 802 facing upward so that the center of the center table 30 of the measurement table 3 and the center of the workpiece 80 substantially coincide with each other. Then, the suction force generated by operating the suction source 39 while the central on-off valve 391 is open is transmitted to the holding surface 300 of the central table 30, so that the central table 30 is covered on the holding surface 300. The central region of the lower surface 801 of the workpiece 80 is held under suction. In this state, the radial opening/closing valve 395, the radial opening/closing valve 396, and the radial opening/closing valve 397 are closed, and the first radial table 321, the second radial table 322, and the third radial table 323 , the suction force is not transmitted to the outer peripheral side of the lower surface 801 of the workpiece 80 . It is in a state where it is not in contact with the holding surface of the third radial table 323.

Under the control of the central cylinder mechanism 90 by the measuring element lowering control means 9, the central measuring element 42 descends at a predetermined speed and the contact 420 comes into contact with the upper surface 802 of the workpiece 80. The thickness at a measurement point 821 (see FIG. 4) at the center of the workpiece 80 is measured. Then, information about the thickness of the workpiece 80 at the center measurement point 821 is stored, for example, in the memory element of the tracing stylus lowering control means 9.

After lowering the center measuring stylus 42 shown in FIG. As a result, the first radial measuring element 44, the second radial measuring element 45, and the third radial measuring element 46 descend one after another from the center of the measuring table 3 toward the outside at a short time interval. .

As a result, as shown in FIG. is pressed against each holding surface of the first radial table 321, second radial table 322, and third radial table 323, so that there is no gap between the lower surface 801 of the workpiece 80 and each holding surface. Place it like this. Further, the support table 33 supports the lower surface 801 of the workpiece 80 with the support surface 335. At this time, the workpiece 80 is sequentially moved outward from the center of the measurement table 3 at short time intervals to each of the first radial table 321, second radial table 322, and third radial table 323. Since the workpiece 80 is pressed against the holding surface, there is no slack in the workpiece 80.

In this embodiment, for example, the gauge head lowering control means 9 performs control to sequentially lower the first radial gauge head 44, the second radial gauge head 45, and the third radial gauge head 46 in parallel. Then, the radial opening/closing valve 395, the radial opening/closing valve 396, and the radial opening/closing valve 397 are energized sequentially or simultaneously, and the radial opening/closing valve 395, the radial opening/closing valve 396, and the radial opening/closing valve are energized. By opening 397, the suction force generated by the suction source 39 is transmitted to each holding surface of the first radial table 321, the second radial table 322, and the third radial table 323. Then, a gap is formed between the workpiece 80 and each holding surface by the first radial table 321, the second radial table 322, and the third radial table 323 in a state where there is no slack or warpage. It is held by suction without any problem. Note that suction and holding of the workpiece 80 by the central table 30 continues.

The thickness of the workpiece 80 at the radial measurement point 822, the radial measurement point 823, and the radial measurement point 824 shown in FIG. Each measurement is made by the third radial measuring element 46, and the measurement information is stored in the storage element of the measuring element lowering control means 9.

Design information regarding the diameter of the workpiece 80, etc. is stored in advance in the probe lowering control means 9. Therefore, by performing thickness measurement using the first radial measuring element 44, the second radial measuring element 45, and the third radial measuring element 46, for example, the center of the measuring table 3 can be The relative position of each radial direction measurement point 822 to radial direction measurement point 824 (X-axis, Y-axis coordinate The measuring stylus lowering control means 9 can grasp and store the position) in association with each measured thickness information.

Next, the third radial cylinder mechanism 93, the second radial cylinder mechanism 92, and the first radial cylinder mechanism 91 are controlled by the measuring element lowering control means 9, so that the third radial measuring element 46 and the second radial direction measurement are performed. The element 45 and the first radial measuring element 44 are raised in this order and separated from the workpiece 80. In addition, by stopping the power supply from the probe lowering control means 9 to the radial opening/closing valve 395, the radial opening/closing valve 396, and the radial opening/closing valve 397 to close them, the first radial table 321 and the second radial opening/closing valve 397 are closed. The suction holding of the workpiece 80 by the table 322 and the third radial table 323 is released. Note that suction and holding of the workpiece 80 by the central table 30 continues, and only the central region of the lower surface 801 of the workpiece 80 is suction-held by the measurement table 3.

Next, the rotating means 36 rotates the central table 30 by a predetermined angle, for example, in a clockwise direction when viewed from the +Z direction. In this embodiment, the rotation angle is 30 degrees, but the rotation angle may be 60 degrees or 15 degrees. As the workpiece 80 rotates by 30 degrees with the rotation of the central table 30, the workpiece 80 shown in FIG. A first radial measuring element 44, a second radial measuring element 45, and a third radial measuring element 46 are positioned. Note that the rotation of the workpiece 80 by a predetermined angle may be performed manually by an operator without providing the rotation means 36 in the thickness measuring device 1.
After that, in the same manner as described above, when the first radial measuring element 44, the second radial measuring element 45, and the third radial measuring element 46 descend, the first radial table 321 and the second radial table 322 and the third radial table 323 suck and hold the workpiece 80, and the workpiece 80 is sucked and held by the first radial measuring element 44, the second radial measuring element 45, and the third radial measuring element 46, which descend in sequence. Thickness measurements are performed at the radial measurement points 832, 833, and 834 of the workpiece 80, and the measurement information is stored in the storage element of the probe lowering control means 9.

Each time the central table 30, which continues to suction and hold the workpiece 80 as described above, rotates 30 degrees, the thickness is measured at the radial measurement point of the workpiece 80, which is indicated by the two-dot chain line circle in FIG. When the center table 30 finishes rotating 360 degrees repeatedly, as shown in FIG. The thickness of the workpiece 80 is now measured at a total of 36 other radial measurement points including the measurement points 832 to 834. Then, the probe lowering control means 9 can recognize the thickness distribution of the workpiece 80 from the thickness information of the workpiece 80 at each of the 37 measurement points.

As described above, the thickness measuring device 1 according to the present invention includes the measuring table 3 that suction-holds the lower surface 801 of the workpiece 80 with the holding surface, the center measuring element 42 arranged directly above the center of the measuring table 3, A plurality of first to third radial measuring elements 44 to 3 are arranged at intervals from the center measuring element 42 in the radial direction of the measuring table 3, and further spaced apart from each other in the radial direction of the measuring table 3. After the center measuring element 42 is lowered by the measuring element lowering control means 9, the first radial measuring element 44 to the third radial measuring element 46 are moved outward from the center of the measuring table 3. By performing control to lower the workpiece 80 in order from the center of the workpiece 80 to the outer circumferential side, the first radial measuring element 44 to the third radial measuring element 46 are sequentially lowered. The thickness is measured while pressing toward the surface to prevent the workpiece 80 from becoming loose and gradually eliminating warpage and eliminating the gap between the holding surface and the lower surface 801, so the thickness of the workpiece 80 with warpage can be accurately measured. It becomes possible to measure

In the thickness measuring device 1 according to the present invention, the measuring table 3 includes a central table 30 that is arranged directly below the central measuring element 42 and holds the lower surface 801 of the workpiece 80 by suction, and a central opening 330 that exposes the central table 30. and a support table 33 that supports the lower surface 801 of the workpiece 80 that is suction-held by the center table 30, and further includes a rotation means 36 that rotates the center table 30 around the center of the center table 30. By doing so, each time the thickness of the workpiece 80 is measured using the first radial measuring element 44 to the third radial measuring element 46, the central table 30 holding the workpiece 80 is moved at a predetermined angle (for example, 30 degrees). By rotating it with the rotating means 36, it becomes possible to measure the thickness at a plurality of radial measurement points in the circumferential direction of the upper surface 802 of the workpiece 80.

In the thickness measuring device 1 according to the present invention, the measuring table 3 includes a first diameter measuring element disposed directly below each of the first radial measuring element 44, the second radial measuring element 45, and the third radial measuring element 46. The support table 33 includes a direction table 321, a second radial table 322, and a third radial table 323, and the support table 33 exposes the first radial table 321, the second radial table 322, and the third radial table 323. By having the radial opening 331, the radial opening 332, and the radial opening 333, the first radial measuring element 44, It becomes possible to measure the thickness of the workpiece 80 using the second radial measuring element 45 and the third radial measuring element 46.

The first radial table 321 to the third radial table 323 are capable of suctioning and holding the workpiece 80, and when the first radial measuring element 44 to the third radial measuring element 46 descend, the first radial table 323 ~ By suctioning and holding the workpiece 80 with the third radial table 323 and measuring the thickness of the workpiece 80, the workpiece 80 can be held without creating a gap between the holding surface and the lower surface 801 of the workpiece 80. 80 thickness can be measured more accurately.

Note that the thickness measuring device 1 according to the present invention is not limited to the above-described embodiments, and the effects of the present invention can be exerted without being limited to each configuration illustrated in the attached drawings. It can be changed as appropriate within the range.
For example, the thickness measuring device 1 shown in FIG. 1 may have a configuration in which the support table 33 is not provided with the radial openings 331 to 333, and the first radial table 321 to the third radial table 323 are not provided. good. In this case, the first radial gauge head 44, the second radial gauge head 45, and the third radial gauge head 46 each measure the thickness of the workpiece 80 on the support surface 335 of the support table 33. conduct.

80: Workpiece 802: Top surface of workpiece 801: Bottom surface of workpiece 1: Thickness measuring device 3: Measuring table 30: Center table 300: Holding surface 303: Suction hole 321: First radial table 322: No. 2 radial table 323: 3rd radial table 325: Fixed member 39: Suction source 390: Central suction path 391: Central on-off valve 398: Rotary joint 392-394: Radial suction path 395-397: Radial on-off valve 33 : Support table 330: Central opening 331 to 333: Radial opening 339: Support column 335: Support surface
36: Rotating means 362: Spindle 363: Motor 42: Center stylus 420: Contact 421: Measuring element body 44: First radial stylus 45: Second radial stylus 46: Third radial stylus 9: Measurement Child descent control means 90: Central cylinder mechanism 91 to 93: First to third radial cylinder mechanisms

Claims (4)

A thickness measuring device that measures the thickness of a warped workpiece by the height of a probe lowered onto the top surface of the workpiece,
a measurement table that suction-holds the lower surface of the workpiece with a holding surface;
a center measuring element located directly above the center of the measuring table;
a plurality of radial measuring elements arranged at intervals from the center measuring element in the radial direction of the measuring table and further spaced from each other in the radial direction of the measuring table;
A thickness measuring device comprising: a measuring stylus lowering control means for lowering the central measuring stylus and then sequentially lowering the radial measuring stylus in order from the center of the measuring table toward the outside. The measurement table is
It has a central table disposed directly below the center measuring element and holds the lower surface of the workpiece under suction, and a central opening that exposes the central table, and has a central opening that exposes the lower surface of the workpiece suctioned and held by the central table. a support table for supporting;
2. The thickness measuring device according to claim 1, further comprising rotation means for rotating the central table around the center of the central table. The measurement table includes a radial table disposed directly below each of the plurality of radial measuring elements,
The thickness measuring device according to claim 2, wherein the support table has a radial opening that exposes the radial table. The radial table is capable of suctioning and holding the workpiece,
4. The thickness measuring device according to claim 3, wherein when the radial measuring element descends, the radial table suction-holds the workpiece to measure the thickness of the workpiece.

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